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No, with one odd exception. The three most testable tales — a heart rate above 140 meaning a girl, the Chinese lunar calendar, and the Drano urine test — were examined together in one study and none predicted better than chance. Severe morning sickness is the exception: it carries a real but far too weak association.
A study published in the Canadian Medical Association Journal took three of the most common tales and tested them against known outcomes: fetal heart rate above 140 beats per minute meaning a girl, the Chinese lunar calendar, and the Drano test, in which a urine sample is mixed with drain cleaner and the resulting colour read as an answer.
None of the three had predictive value. That is a stronger result than it sounds, because it is rare for folklore to be tested at all — most of these tales have simply never been examined, which is not the same as having been examined and passed.
The heart rate claim has had the most attention since, because it sounds the most medical. A review of 655 fetuses in the first trimester found no meaningful difference in heart rate between male and female fetuses. A 2023 systematic review in BMC Pregnancy and Childbirth went back over the conflicting earlier work and concluded that first-trimester heart rate is not a reliable predictor.
A 2018 study using cardiotocography did find male fetuses had a slightly lower baseline rate with a little more variability — but the differences were small, within the range of normal variation, and nowhere near large enough to call an individual pregnancy.
There is also a timing problem that no amount of data fixes: sex is settled at conception by which chromosome arrives. A heart rate measured at twelve weeks is not reporting on it.
Severe morning sickness is the exception, and it is instructive about why the others fail. Hyperemesis gravidarum — vomiting severe enough to need hospital treatment — is associated with carrying a girl. One study of 166 women admitted for it reported an odds ratio of about 1.6, and describes the association as well established in European and North American populations.
An odds ratio of 1.6 is a real population-level signal and a useless individual one. It shifts the odds from roughly 50/50 to roughly 60/40 among women sick enough to be hospitalised — not among women who felt rough in the first trimester, which is most of them. It is the difference between a finding and a prediction.
Carrying high or low, craving sweet rather than salty, the shape of the bump, the ring-on-a-string test, the baking soda test, the key test, skin and hair changes: none of these has been tested in any study we could find.
Where a mechanism has been proposed, it tends not to survive contact. How high a bump sits is governed by abdominal muscle tone, the shape and position of the uterus, the baby's lie, and how many previous pregnancies there have been — all of which vary enormously and none of which is downstream of the baby's sex.
That does not make them harmful. A bet with your partner over a craving costs nothing and is part of the fun of a pregnancy. It is worth knowing which ones have been checked and which are simply traditions, so you can enjoy them on the right terms.
The two methods that do give an answer are a non-invasive prenatal test, which reads placental DNA from a sample of the mother's blood from about nine or ten weeks, and the anatomy scan at eighteen to twenty-two weeks.
No. A review of 655 fetuses found no meaningful difference in first-trimester heart rate between male and female fetuses, and a 2023 systematic review concluded heart rate is not a reliable predictor of sex.
It was one of three myths tested in a study published in the Canadian Medical Association Journal, and it showed no predictive value. It is a tradition worth enjoying as a tradition, not a method — which is how our own Chinese gender predictor presents it.
It shifts the odds slightly. Hyperemesis gravidarum — sickness severe enough to require hospital treatment — is associated with carrying a girl, with a reported odds ratio of about 1.6. That is a real association across a population and far too weak to tell you anything about your own pregnancy.
No. Where the bump sits is determined by abdominal muscle tone, the shape and position of the uterus, how the baby is lying, and how many pregnancies came before. None of those depends on the baby's sex.
No, and it does not work either. It was one of the three myths found to have no predictive value, and mixing urine with drain cleaner can release harmful fumes. There is no reason to try it.
A non-invasive prenatal test from about nine or ten weeks, which reads placental DNA from the mother's blood, or the anatomy scan at eighteen to twenty-two weeks.